Syncope is defined as a sudden but brief loss of consciousness with postural collapse, resulting from decreased cerebral blood flow, and spontaneous recovery that does not require resuscitative measures. According to the Framingham Study, syncope occurs in 3% of men and 3.5% of women, especially among the elderly, and is responsible for 3% to 6% of all hospital admissions.

Vasovagal (neurocardiogenic) syncope is the most common noncardiac cause (50% of all cases), followed by orthostatic hypotension. Cardiac causes of syncope are either related to obstruction of cardiac output or disturbances of cardiac rhythm. The causes of syncope are often classified into three categories.

• Noncardiac causes—vasovagal (vasodepressor) responses; orthostasis; cerebrovascular disease; carotid sinus sensitivity; gastrointestinal hemorrhage, other blood loss or other causes of hypovolemia; situational (cough, micturition, defecation, deglutition, hypoxia, hypoglycemia, hyperventilation, psychogenic, migraine)
• Cardiac causes—obstructions: aortic stenosis, pulmonary embolism, pulmonary stenosis, pulmonary hypertension, mitral stenosis, hypertrophied cardiomyopathy, cardiac myxoma, prosthetic valve malfunction; arrhythmias: ventricular tachycardia/fibrillation, sinus bradycardia (sick sinus syndrome), supraventricular tachycardia, atrioventricular block, myocardial infarction, pacemaker malfunction, prolonged QT syndrome
• Unknown cause—30% to 45% of cases 

• Age (>65 years of age) 
• Preexisting heart disease 
• Recreational drugs (e.g., cocaine) 
• Medications (e.g., antihypertensives, insulin, oral hypoglycemics, diuretics, antiarrhythmics, anticoagulants via blood loss) 

• Presyncope: lightheadedness, blurred vision, diaphoresis, heaviness in the lower limbs, giddiness, confusion, yawning, nausea, and sometimes vomiting 
• Syncope: pallor, loss of consciousness, loss of postural tone, myoclonic jerks, feeble pulse, low blood pressure, imperceptible breathing, recovery of consciousness within a few seconds to minutes

Although syncope is a fairly straightforward diagnosis, distinguishing among the numerous causes of syncope can be difficult. It is most important to distinguish syncope from seizures or hypoglycemic reactions in diabetics; after this distinction is made, it is imperative to distinguish cardiac from noncardiac causes.

Evaluation of the patient with syncope involves a detailed history, physical examination, and special diagnostic tests, focusing on the symptom complex of the present episode, medications taken, preexisting medical conditions, and descriptions of similar previous episodes. Fainting patients are pale, motionless, diaphoretic, hypotensive, with a weak or absent pulse and shallow respirations. Orthostatic vital signs should be measured as part of the exam, particularly just following an episode when a patient presents to a hospital emergency room or other acute care facility. The patient should also be observed on a cardiac monitor.

The following studies may be warranted depending on clinical circumstances:

• Complete blood count—to determine the presence of anemia 
• Serum electrolytes to determine the presence of electrolyte deficiencies that may cause arrhythmias
• Glucose - to assess for hypoglycemia

• Vasovagal syncope: impaired sympathetic drive, diminished venous return, and venous pooling, resulting in inappropriate vasodilation, bradycardia, and hypotension 
• Cardiac syncope: reduction in cardiac output usually from a cardiac arrhythmia (<35 to 40 beats/min and >180 beats/min), resulting in reduction in cerebral perfusion
• Orthostatic hypotension: autonomic dysfunction secondary to diabetes mellitus, syphilis, alcoholism, amyloidosis, or adrenal insufficiency; hypovolemia secondary to hemorrhage, vomiting, diarrhea, drugs, or low fluid or sodium intake

The following may be indicated under certain clinical circumstances:

• Magnetic resonance imaging (MRI) of the head or brain to identify focal neurologic deficits or intracranial abnormalities
• Echocardiography—to identify cardiac structural or functional abnormalities
• Nuclear lung scan, pulmonary angiography, duplex ultrasound, or venography—to look for venous thromboembolic disease 

The following may be indicated under certain clinical circumstances:

• Tilt table testing with or without isoproterenol (1 to 5 mg/min for 30 min) infusion (to enhance sensitivity)—to provoke a neurocardiogenic response 
• Electrocardiogram (ECG)—to determine an underlying cardiac problem (e.g., arrhythmia, conduction abnormalities, ventricular hypertrophy, QT prolongation, pacemaker malfunction, myocardial infarction) 
• Transtelephonic ECG monitoring (event recorders)—to diagnose causes of syncope over weeks to months 
• Signal-averaged ECG—to identify ventricular arrhythmias, especially in patients who have had a myocardial infarction 
• Electroencephalogram (EEG)—to differentiate seizures from syncope 
• Electrophysiology studies—to determine the presence of cardiac rhythm disturbances, especially ventricular tachycardia 

Physicians should be alert to the malignant causes of syncope (e.g., internal bleeding, myocardial infarction, complete heart block, ventricular tachyarrhythmia) so that life-threatening situations do not ensue. The benign faint can be treated by placing the patient in a position that increases cerebral blood flow (e.g., head lower than the heart), loosening all tight clothing, applying cold water to the face, and preventing emesis or choking by turning the head to the side.

• Beta-adrenergic antagonists, disopyramide, theophylline, scopolamine, ephedrine—to treat vasovagal syncope
• Mineralocorticoids and salt loading—to correct hypovolemia or venous pooling

Placement of a cardiac pacemaker for symptomatic bradycardia or some tachyarrhythmias.

As discussed earlier, syncope may be preceded by a trigger along with warning symptoms. Autogenic training, diaphragmatic breathing, progressive muscle relaxation, and biofeedback have been successfully utilized to increase awareness of presyncopal symptoms and to reduce autonomic activity in the case of vasovagal syncope (McGrady et al. 1997). Nutrition, herbs, and acupuncture may also play a role in the treatment of syncope.

As discussed earlier in the monograph, hypoglycemia may be associated with syncope. Even modest decreases in blood glucose levels can act synergistically with hypotension and hypocapnea in particular to induce a loss of consciousness. In one study, glucose levels were assessed in 16 patients with presumed vasovagal syncope. Hypoglycemia was consistently found in all patients experiencing syncope (Salins et al. 1992), suggesting that low blood sugar may be the etiology at times, rather than the presumed vasodepression. Syncope may be even more prominent in elderly patients with poor glycemic control who commonly suffer from postprandial hypotension (Jansen and Lipsitz 1995). These case reports and the Jansen and Lipsitz trial illustrate the importance of adequate nutritional intake in those with a history of syncope as well as the elderly. In the case of dysglycemia, avoidance of refined foods and sugar as well as eating small, frequent meals high in protein are generally recommended. 

Licorice root (Glycyrrhiza glabra) contains mineralocorticoid properties that expand intravascular fluid volume. A case study of a 38-year-old male with a history of vasovagal syncope responded well to a trial of high-salt diet and treatment with licorice root (520 mg bid); resolution of symptoms and syncopal episodes was achieved within one week. A withdrawal of the herb over several days resulted in resumed symptomology. The patient remained normotensive on this therapy and serum electrolytes remained within normal range. While licorice root is often deglycyrrhated to remove the active mineralocorticoid constituent, this property may be of benefit in select populations. This herb is contraindicated in patients with hypertension, hypokalemia, severe kidney disease, and pregnant women (Blythe 1999); even with normotensive patients, blood pressure should be monitored while taking licorice every four to six weeks initially, followed by every three to six months when stable.

Many herbs have cardiotoxic side effects when used indiscriminately. Natural does not necessarily imply safe and herbal therapies should only be used under the supervision of an experienced health care provider. A case of self-medication with tincture of aconite resulted in severe bradycardia, reversible conduction defect, hypotension, and syncope (Guha et al. 1999).

There are some herbal remedies, used alone and in combination, which are considered cardioprotective in general. One example includes hawthorn (Crataegus monogyna). While not specific for cardiac causes of syncope, some clinical experts suggest the value of hawthorn for maintenance of blood pressure, myocardial perfusion, and treatment of arrythmias (Murray and Pizzorno 1999).

An experienced homeopath would consider the individual's constitution and determine an appropriate treatment. Although no known studies in the literature have specifically tested homeopathic remedies, the following are used clinically by many homeopaths for the treatment of recurrent syncope and pre-syncope:

• Carbo vegetabilis for syncope or lightheadedness after rising in the morning; from loss of fluids; or from becoming overheated. Patients appropriate for this treatment are generally chilly and pale at the time of presentation.
• Opium for syncope due to excitement or fright. Patients appropriate for this treatment are generally sweaty, glassy-eyed, and trembling at the time of presentation.
• Sepia for syncope following prolonged standing, exercise, or secondary to fluid loss from fever. Patients appropriate for this treatment feel hot during the syncope episode but cold immediately afterwards.

The Chinese medical model of syncope consists of five categories of symptomatology: dying out of yang, dying out of yin, qi syncope, crapulent syncope (due to excess eating or drinking), and phlegm syncope. A clinical analysis of 102 critical cases of syncope treated with acupuncture and moxibustion was presented. Eighty seven patients were considered semi-comatose; fifteen were comatose. Traditional Chinese and Western drugs had been ineffective in reviving these patients. Treatment consisted of regulating yin and yang with acupuncture and reinforcing qi with moxibustion, then regulating qi and blood and dredging the channels to resuscitate the patient. Resuscitation efforts were based on the presenting symptoms. The intent was to evaluate and treat the underlying disease after the patient regained consciousness as well as normal blood pressure, pulse, and respiration (Shifa and Shiping 1990).

Results were reported as follows: "excellent" in 40 patients, "good" in 38, "fair" in 3, and "failed" in 21. In the excellent to good categories, patients were conscious; pulse was either normal or nearly normal and stabilized; and drug intervention was at least partially suspended while treating with acupuncture and moxibustion. ("All drugs" included Traditional Chinese Medicine as well as conventional medications.) Those with "fair" results were conscious; their blood pressure was nearly normal but not stabilized; and their pulse was "scattered and weak." Those whose treatment failed were not able to be resuscitated from the coma and died after all treatments failed—Western medication and TCM, including acupuncture and moxibustion (Shifa and Shiping 1990).

The application of acupuncture is known for its virtual absence of side effects and complications; however, it is not uncommon to observe syncope in patients during acupuncture treatments. This type of syncope, called "needle fainting" in Chinese medicine, belongs to the category of vasodepressor syncope. In a year-long clinical study of 28,285 total acupuncture therapy procedures, 49 patients experienced needle fainting once and three patients experienced it twice. Management consisted of immediate removal of all needles and vigorous stimulation of the Jen-Chung point (Gv 26, located between the nose and upper lip), as well as placing the patient in a recumbent position. All of the patients who experienced syncope were upright when the episodes occurred. Patients with anxiety or fears about acupuncture were more likely to faint during the first visit, while patients with underlying cardiovascular complications (e.g., hypertension, arrhythmias) were more likely to faint during subsequent visits. Needle fainting is not a serious complication of acupuncture and may be easily remedied by needling susceptible patients appropriately while in the recumbent position (Fang-Pey et al. 1990).

No corroborating evidence has been found with respect to massage and syncope.

Many patients, especially the elderly and those with preexisting cardiac disease, may benefit from hospitalization both to prevent further episodes (thereby avoiding serious injury or death) and to perform diagnostic tests. Continuous ambulatory ECG monitoring can identify arrhythmias as a cause of syncope, especially in patients who experience recurrences.

Prevention of syncope is dependent on the cause.

• Vasovagal syncope due to fatigue, hunger, emotional upheaval—avoid these circumstances; see the Nutrition section under Treatment Options for more specific ideas.
• Orthostatic syncope—avoid changing positions quickly, especially rising from a recumbent position, wear elastic stockings to prevent pooling of blood in the lower legs, and avoid situations requiring prolonged standing; find alternatives to medicines that can cause orthostasis such as diuretics, antidepressants, sympatholytic antihypertensive drugs, and beta-blockers. See also the section under Complementary and Alternative Therapies for more ideas on how to prevent orthostatic syncope.
• Carotid sinus syncope—avoid tight clothing around the neck area; turn the whole body, not just the head, when looking around.
• Recurrent syncope—cover all floors, including in the bathroom, with thick carpeting and avoid driving or operating mechanical equipment.
• Avoid caffeine which may exacerbate hypoglycemia.
• Avoid alcohol which may lead to hypotension by causing vasodilation.

Elderly patients are at increased risk for injury after a syncopal episode, especially fractures or intracranial hemorrhage, which in turn may lead to hospitalization, immobility, pneumonia, and even death.

The one-year mortality rate for syncope associated with heart disease is roughly 20% to 30%; for non-cardiac syncope it is 0% to 6%; and with syncope from an undetermined cause, 6%.

Paradoxically, the normal treatment for syncope (placing the patient in the supine position to increase cerebral blood flow) may actually worsen the inadequate perfusion in the pregnant patient caused by the enlarged uterus, which prevents venous return. The correct position is left lateral decubitus. Varicose veins, which are common in pregnant women, may predispose the pregnant woman to syncopal episodes as they increase the pooling of blood in the extremities.

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